This invention relates to an open-end friction spinning machine having a large number of spinning units arranged next to one another, each containing two friction rollers arranged next to one another which, by means of a joint drive, are driven in the same rotational direction and which, with their shell/cover surfaces, form a wedge-shaped gap serving as the yarn forming region or point.
In the case of an open-end friction spinning machine, it is advantageous to drive all spinning units, at least on one machine side, by a joint drive, as this is known, for example, for a single unit (see European Patent EP-PS No. 52 412). When servicing work is carried out at a single spinning unit, it is in many cases necessary to interrupt the drive of the rollers of this spinning unit without disturbing the adjacent spinning points of the other spinning units. In this case, it is often necessary, during the servicing work, especially during a yarn piecing operation, to drive the rollers at rotating speeds that deviate from the normal spinning operational rotating speeds.
The invention is based on the objective of developing an open-end friction spinning machine of the initially mentioned type in such a way that it is possible to drive the rollers of a spinning unit at an arbitrarily adjustable speed that is not dependent on the operational drive for normal spinning operations.
This objective is achieved according to an important aspect of the invention by providing a servicing apparatus which can be selectively applied in each case to one spinning unit, said servicing apparatus having an auxiliary drive for the rollers containing an auxiliary driving element that can simultaneously be applied to the shell or cover surfaces of both rollers. By means of this arrangement of the invention, it is possible to drive the rollers of one single spinning unit at a desired speed independently of the normal spinning operational drive. Since the auxiliary drive is applied directly at the shell surfaces of the rollers, the drive can very sensitively adjust the desired speeds, since no transmission or similar means exist between the point of application of the auxiliary drive and the rollers.
According to a further aspect of preferred embodiments of the invention, it is provided that the auxiliary drive contains a joint driving element that runs simultaneously against the shell surfaces of both rollers. This also extensively simplifies the operational drive via the auxiliary servicing apparatus.
According to an advantageous development of the invention, it is provided that the servicing apparatus is equipped with means for interrupting the normal operational drive of the rollers by detaching the joint driving element from both rollers. Thus, it is avoided that the operational drive and the auxiliary drive affect the rollers at the same time.
According to another advantageous development of certain preferred embodiments of the invention, it is provided that each spinning unit is equipped with means for interrupting the drive of the rollers by detaching the joint driving element from both rollers. In the case of this development, it is provided that the spinning unit itself, for example, as a function of a yarn breakage, already interrupts the operational drive of the rollers, before the servicing apparatus becomes operative.
In order to provide an operational drive for the rollers that is as simple as possible and that also permits an interruption by simple means, a tangential belt is provided as the joint driving element which passes through in longitudinal direction of the spinning machine resting against the shell surfaces of both rollers of the respective spinning units, and which at each spinning unit, by means of a tension roll arranged in the plane of the wedge-shaped gap, is loaded in the direction of the shell surfaces of the rollers. In the case of this arrangement, it is ensured in a simple manner that both rollers that are driven in the same rotational direction are driven and loaded evenly by the tangential belt. In this case, the construction of the drive is very simple since only one tension roll is required. The result is that then the means for interrupting the drive can be constructed correspondingly simply since only the one tension roll and possibly also the tangential belt must be moved away from the rollers.
In a further development of the invention, at least one brake lining held by a spring is mounted at a lever holding the tension roll. This brake lining can be applied to the shell surface of a roller when the lever is adjusted to the inoperative position. Consequently, with the interruption of the operational drive, a braking of one of the rollers is caused, especially of the roller rotating into the wedge-shaped gap, which has the result that fiber or yarn residues located in the wedge-shaped gap after a yarn breakage can be removed easily therefrom.
Further objects, features, and advantages of the present invention will become more apparent from the following description when taken with the accompanying drawings which show, for purposes of illustration only, embodiments in accordance with the present invention.